Barrel Twist Tolerance Specs?

[ridgeway]

Just out of curiosity, do barrel manufacturers provide a tolerance specification on barrel twist? I have yet to come across a barrel that hits exactly what is specified. Maybe its my measuring technique? Just wondering.

I use a tight patch part way down the bore. I mark a starting point on my rod. Mark a hash mark on the rod handle and rod itself for a staring point. Push the rod in carefully till my hash mark makes a complete rotation. Mark the rod at the same reference point as the starting point. Remove and measure. This has been extremely consistent.

 

[Rustystud]

Barrel makers and barrel specs. I used a barrel maker back in 2005 and the beginning of 2006. His barrels were pull button. He would mark bore and land depth on the tenons. I owned both pin gauges and reamer bushings in .0001" increments. When I checked the bore diameters I did not come up with the same measurements. after having several barrels that had issues I changed barrel makers. The new barrel makers measurements were also marked on the tenon. I found at room temperature the marked measurements were pretty darn close. Another very reputable gunsmith told me to slug the barrels. This would provide information that one can not see with the naked eye.

A few years down the road I talked to several former employees of the first barrel maker. They told me the first barrel maker did not even have any tooling/indicators/gauges to measure the bore diameters and he just marked them what he thought they should be. To say the least I felt violated having trusted the first barrel maker.

A few years ago I got some barrels from another "quality" barrel maker. The barrels looked (bore scoped) and felt good (slugged) but developed pressure before they developed velocity. After contacting the barrel maker they asked that I check the land/groove width. I slugged the barrel and measured the land width. the lands were about .005" -.008" to wide. (improper land groove ratio). The barrel maker replaced 16 barrels I had in inventory no questions asked.

I would dare say only a few shooters and gunsmiths really know and understand how barrels work. There are a few barrel makers who also are in the business without a clue and are not completely honest with their customers. I have spent a great deal of time studying about barrels and talking with barrel makers. Proper steel, tooling, straight drilling, reaming, pre and post lapping, good buttons or cutter hook geometry, and stress relieving are the key to good barrels.

There are a few barrel makers who are very knowledgeable and make great products.

Do your homework, study and ask the right questions.

Nat Lambeth

 

[ridgeway]

Thanks Nat!